Recently, a scaling-down has been in progress through a plasma processing, demanding for a line width of 20 nm or less to be formed on a wafer by an etching process. Therefore, a generation of a fine particle having a size, which has been treated as being nonproblematic in a conventional plasma processing, has become problematic. Particularly, for example, if the fine particle having a size of 60 nm or less falls onto a pattern formed on a wafer, a line having a line width of, e.g., 20 nm, becomes short-circuited, or the fine particle hinders a following process such as etching, deposition or the like, so that a line may not be formed. In other words, a so-called killer defect occurs. Hence, a region where designed electrical characteristics are not obtained is generated in the wafer, which leads to a decrease in productivity. Accordingly, in comparison to the conventional case, a recent demand for finer processing and a demand for a reduction and removal of fine particles have been markedly increased.
Generally, a processing chamber of an etching apparatus is made of metal such as aluminum or the like, and inner surfaces of the chamber are exposed to a plasma during plasma processing. Thus, a base material of the chamber wall exposed to the plasma is coated with a plasma-resistant member to suppress a generation of particles caused by the etching of the inner wall of the chamber by the plasma.
As for a plasma-resistant member, a thermal-sprayed film of yttrium oxide Y2O3 is recently widely used. If a CF-based gas is supplied into the chamber in case of using the thermal-sprayed film of yttrium oxide Y2O3, yttrium oxide Y2O3 is consumed by a reaction with the CF-based gas.
Therefore, in Patent Document 1, inner surfaces of a chamber exposed to a plasma are coated with yttrium fluoride YF3 serving as a plasma-resistant member.
Patent Document 1: Japanese Patent Application Publication No. 2002-252209
However, in Patent Document 1, the inner surfaces of the chamber exposed to the plasma are coated with yttrium fluoride in order to solve the problem in which the plasma-resistant member is consumed when a CF-based gas is supplied into the chamber. Further, the technical background of the recent miniaturization technique is completely different from that of Patent Document 1 that has been published more than ten years ago, because the pattern, which is micro-processed in conformity with the recent demand, cannot be formed by the pattern forming technique of Patent Document 1. Therefore, in the case of supplying a plasma gas containing a gas including a CF-based gas and other gases into the chamber, Patent Document 1 does not provide the solution for preventing fine particles from causing a so-called killer defect by suppressing the generation of the fine particles each having a size of about 60 nm or less.